Small Hydropower Plant in Noryangjin Reservoir
 
Hydroelectric power is a type of renewable energy that uses head and flow of moving water to produce energy; small hydropower (SHP) in particular is the result of the development of hydroelectric power on a scale serving a small community or with capacity of up to 10,000kW in general. SHP eliminates pollutants and allows the constant supply of electricity. Note, however, that it has not been widely adopted in Korea due to difficulties involving high initial investment cost and plant site selection.
Our Arisu small hydropower plant takes advantage of the kinetic energy of non-pressurized water or head (difference between upstream and downstream water levels) of 24 meters, which is produced in the Amsa purification center and Noryangjin reservoir. This is the first time waterwheel is installed in the drinking water supply network to produce hydropower.
Currently, the 103MWh per month generated through this system is being purchased by KEPCO (Korea Electric Power Corporation) for 1.6 million won every month.
In line with Seoul’s “One Less Nuclear Power Plant” project, the Arisu SHP is expectedto play a pivotal role in solving the electricity shortage in the country and reducing CO2 emissions; thus contributing to the country‘s wider environment preservation initiative.

Installing small hydropower plants: generation capacity of 300 kW (100 kWx3 ea.)
<< Using water flowing from the Amsa purification center to the Noryangjin reservoir, we built the country‘s 1st small hydropower plant where waterwheel is installed in the drinking water supply network.
<< The Seoul Metropolitan Government is selling electricity from SHP‘s monthly generation capacity of 103 MWh, earning income of 1.6 million won every month.

Electricity production capacity could not meet the rapid increase in electricity demand.
The ratio of aggregate electricity consumption to GDP in Korea is 0.44 kWh/$, which is far higher than the OECD average of 0.2 kWh/$. On top of such high energy consumption pattern, Korea‘s reserve electricity has been falling short in the midst of occasional surges in demand caused by abnormal weather patterns such as heat wave, cold wave, etc.
Nuclear power plants can no longer be the answer to address the shortage issue due to strong opposition to this type of energy generation. The opposing voice has gained steam especially after the Fukushima accident in March 2011 and after a scandal that involved fake certificates for some parts in the nuclear reactors in Korea.
 
Seoul is moving forward in line with the government‘s renewable energy policies.
In Korea, 91.9% of power is generated by thermal and nuclear energy, whereas other advanced nations are expanding the portion of renewable energy for their stable supply of electricity. Following suit, the Korean Ministry of Trade, Industry, and Energy (MOTIE) has been implementing various policies and making investments such as Green Home, Green Building, and Green Community. The Arisu hydropower project is part of such government initiative to support municipalities in adopting more renewable energy projects.
 
Environmental preservation has become a social issue.
As citizens have become more aware of the direct and indirect impacts of global warming, rise in sea level, endocrine-disrupting chemicals, and other environmental issues, they recognize the need to preserve the environment and ask the government to do its part and to engage more in the cause.

Global Trend
Having recognized the economic and social benefits of SHP, many advanced countries around the world have already acquired hydrologic statistics and technology in this field. These countries regard SHP not only as a source of energy but also as an important energy industry, and they have already established an assessment method as to the feasibility of SHP as well as optimal design for plants, streamlined, standardized waterwheels system, and automatic control system, all of which have contributed to the wider adoption of SHP globally.
 • China: 38,500MW, Japan: 1,700MW, Germany: 1,600MW, France: 1,956MW, Italy: 2,233MW
 
Other countries have developed low-head waterwheels since low-head units are much smaller in capacity than the conventional large hydro turbines but just as economically viable.
 • Higher capacity means more economical options. Korea (around 1,400kW), Other countries (around 1,000kW)
 
Policies and Institutions of Other Countries
Governments around the world have adopted various systems considering their own situations in terms of demand, supply, generation capacity, and production level.

Domestic Trend
In Korea, as of the end of 2010, SHP generation capacity was 95,220kW at 68 plants, and annual SHP generation, 3.39 million kWh.

SHP plants constructed before 2000 were mostly run by IPPs, but the trend reversed after 2001 when the government began various projects including Feed-in-Tariff. Since then, most of the SHP plants have been controlled by municipalities or other public corporations.
Currently, SHP is not utilized to the full extent compared to its high potential. In fact, SHP can be adopted in agricultural reservoirs and sewage treatment plants; hence the huge room for adoption. With RPS now adopted in Korea, SHP is becoming an even more economical option in which many are interested in investing.

Process of Policy Implementation
 • 2012.02.25: Report on measures to implement the lessons learned from the Mayor‘s visit to Japan (pilot project for 1 SHP, 1 PV)
 • 2012.03.13: Report on how to adopt SHP
 • 2012.10.10: Secured budget for investment in SHP (1.231 billion won appropriated by the Korean Ministry of Knowledge Economy)
 • 2013.04.04: Working design
 • 2013.07.02: Service performance
 • 2013.10.16: Permit as utility enterprise (generation 300kW)
 • 2013.08~2014.01: SHP plant construction
 • 2014.01.29: Construction completed

Arisu SHP plant
 • Project Overview
   - Location: Noryangjin Reservoir in Seoul
   - Transmission Pipe: 23.2 km (diameter: 2,200 mm) of water pipes from the Amsa purification plant to the Noryangjin reservoir
   - Water Level: head of purification plant (upstream): 37.79m, head of reservoir (downstream): 12m
   - Waterwheels (3 units): pump-turbine type, rated capacity of 94kW, maximum output of 107kW
   - Generators: three-phase induction generator (capacity: 100kW x 3EA)
   - Operation: Automatic, remote control from the central control center at the Noryangjin reservoir
 • Budget: 2,341 billion won (central government: 50%, city government: 50%)
 • Characteristics
   - A natural effective head of 10m is guaranteed.
   - A large amount of water (daily average of 300,000m3) flows to the reservoir.
   - No additional establishments or structures are required.
   - There is no impact (noise, vibration, other environmental impact) on the surrounding areas; therefore, there is little concern of civil complaints.

Concerns of potential threat to water quality
There were concerns of oil leaks from waterwheels, which could affect 800,000 households. After thorough inspections including numerous discussion sessions with expert advisory groups, more than 20 times of site inspection, and analysis of overseas cases studies, we selected noncorrosive, pump-type waterwheels that can ensure lubricant-free operations, eliminating any possibility of oil leaks.
Other concerns existed as well. Sudden changes in pressure to the pipeline could cause slime formation that pollutes water. Moreover, mid-valve operation to increase water flow – a necessary step to compensate for the pressure loss when SHP is in operation -- could drastically change the water velocity, which could also damage the water quality. To prevent these problems, we implemented measures such as generator pilot operation, monitoring of parameters of water quality in real time, and adjustment of mid-valve.

Technical issues regarding construction
To ensure that our construction works do not affect the households in Seoul, we made sure we took advantage of a special piping technology that eliminates the possibility of water interruptions during the construction in 4 sites. We also used pipe sleeves to prevent pipes from being pushed under pressure and strengthened the support fixtures to be used for water pressure simulation.
To compensate for the limited space in workstation, we had 2 workers in 1 group when carrying materials to pump stations and contracted a company specializing in such operations. Most importantly, all safety measures and accident prevention measures were in place with our inspectors, who stayed at the sites throughout the construction period.

Contributing to the energy reduction initiative of the Government and the Seoul Metropolitan City
Our SHP generation helped realize C02 reduction of 1,032 tons/year and energy saving of 482 TOE/year.

※ TOE(Ton of Oil Equivalent): 1 toe = 107kcal

In addition, 2,286 MWh of power generated by SHP were sold for 0.5 billion won/year to KEPCO, creating revenue for Seoul.
 
Raising awareness and educating on renewable energy
Our SHP project has been documented in the form of video materials, which are being used for middle and high school students in Korea to teach them various sources of energy and the importance of energy. We also promoted our SHP project via broadcasting and newspaper outlets to raise public awareness of renewable energy.

Seoul’s SHP plant using water supply pipelines can be applied to other municipalities in Korea as well as other developing countries in Southeast Asia and South America.

Where would more SHY plants be installed in the future?
We are looking into sites with lower head (over 2m) such as Yeongdeungpo Purification Station (200kW) and Samsung Reservoir (30kW).